As regular CFZ-watchers will know, for some time Corinna has been doing a column for Animals & Men and a regular segment on On The Track... particularly about out-of-place birds and rare vagrants. There seem to be more and more bird stories from all over the world hitting the news these days so, to make room for them all - and to give them all equal and worthy coverage - she has set up this new blog to cover all things feathery and Fortean.

Thursday 4 February 2016

The magnetic compass of birds is affected by polarized light

Date:January 26, 2016
Source:Lund University

The magnetic compass that birds use for orientation is affected by polarised light. This previously unknown phenomenon was discovered by researchers at Lund University in Sweden.

The discovery that the magnetic compass is affected by the polarisation direction of light was made when trained zebra finches were trying to find food inside a maze. The birds were only able to use their magnetic compass when the direction of the polarised light was parallel to the magnetic field, not when perpendicular to the magnetic field.

"We were expecting an effect, but not one so major that it would lead to complete disorientation when the direction of the polarisation of light was perpendicular to the direction of the magnetic field," says Rachel Muheim, who was in charge of the study.

It is still unclear how the different directions of polarised light in relation to the Earth's magnetic field affect birds in the wild. The researchers have put forward a thesis that the birds use it to accentuate the magnetic field during sunrise and sunset -- times of day when migratory birds are believed to determine their direction and calibrate their compasses before migrating.

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